title: Pseudomonas fluorescens biofilms subjected to phage phiIBB-PF7A.
abstract: BACKGROUND
  Pseudomonas fluorescens is an important food spoilage organism, usually found in the form of biofilms. Bacterial biofilms are inherently resistant to a variety of antimicrobial agents, therefore alternative methods to biofilm control, such as bacteriophages (phages) have been suggested. Phage behavior on biofilms is still poorly investigated and needs further understanding. Here we describe the application of phage phiIBB-PF7, a newly isolated phage, to control P. fluorescens biofilms. The biofilms were formed under static or dynamic conditions and with or without renewal of medium.
  
  
  RESULTS
  Conditions for biofilm formation influenced the feature of the biofilm and the morphology of P. fluorescens. Biomass removal due to phage activity varied between 63 and 91% depending on the biofilm age and the conditions under which the biofilm had been formed and phages applied. Removal of the biofilm by phage treatment was faster in younger biofilms, but the same number of surviving cells was detected in all tested biofilms, after only 4 h of treatment, even in older biofilms. Under static conditions, a 3 log higher number of phage progeny remained either inside the biofilm matrix or attached to the substratum surface than under dynamic conditions, pointing to the importance of experimental conditions for the efficacy of phage entrapment into the biofilm.
  
  
  CONCLUSIONS
  Phage phiIBB-PF7A is highly efficient in removing P. fluorescens biofilms within a short time interval. The conditions of biofilm formation and applied during phage infection are critical for the efficacy of the sanitation process. The integration of phages into the biofilm matrix and their entrapment to the surface may be further beneficial factors when phage treatment is considered alone or in addition to chemical biocides in industrial environments where P. fluorescens causes serious spoilage.
authors.affiliation: IBB-Institute for Biotechnology and Bioengineering, Centre of Biological Engineering, Universidade do Minho, Campus de Gualtar 4710-057, Braga, Portugal. s.sillankorva@deb.uminho.pt
authors.forename: Sanna
authors.initials: S
authors.lastname: Sillankorva
authors.forename: Peter
authors.initials: P
authors.lastname: Neubauer
authors.forename: Joana
authors.initials: J
authors.lastname: Azeredo
mesh_terms: D001422:Bacterial Adhesion; D018441:Biofilms; D015169:Colony Count, Microbial; D003612:Dairying; D004866:Equipment Contamination; D005516:Food Microbiology; D050296:Microbial Viability; D008855:Microscopy, Electron, Scanning; D017105:Pseudomonas Phages / Q000254:growth & development*; D011551:Pseudomonas fluorescens / Q000254:growth & development / Q000821:virology*; D012499:Sanitation; D012722:Sewage / Q000382:microbiology; D013193:Stainless Steel
chemical_list: D012722:Sewage; D013193:Stainless Steel